This invention relates to fixture positioning devices of the type which require precise positioning in X and Y directions. Such fixture positioning devices are used, for example, in the manufacture of semi-conductor devices or integrated circuits to hold the projection masks and the silicon wafers during the photolithographic process. A typical manufacturing procedure involves moving one fixture carrying the wafer, which is sometimes known as a "wafer theta plate" into approximate position with a coarse positioning device, moving another fixture carrying the photographic mask, sometimes called the "mask theta plate" into approximate position, and then making fine adjustments to precisely align the projection mask and the wafer. A well-known commercially available automatic machine for carrying out this procedure, as well as optical projection printing of mask designs onto wafers for semi-conductors and integrated circuits, is known as MICRALIGN.RTM., manufactured and sold by SVG Lithography Inc. The MICRALIGN machine employs coarse and fine adjusting devices to move the wafer and mask theta plates in X and Y directions. The theta plates are positioned with "flexure supports" connected between the fixture (or theta plate) and the coarse positioning device, which is usually a gear box and motor driving a linkage mechanism. Each flexure member is designed to move the fixture along one axis only, but to permit freedom of movement along an axis which is perpendicular to it. This is accomplished by using a long slender wire running along the first axis, which permits free movement perpendicular to it by flexing of the wire.
While the commercially available fixture positioning devices of this type have been satisfactory in many regards, problems are encountered when attempting to use a fine positioning device to make final adjustments along the axis of the flexure support.
Accordingly, one object of the present invention is to provide an improved flexure support for a fixture positioning device of the type described.
Another object of the invention is to provide an improved flexure support for a wafer theta plate in an optical projection printing unit.
Another object of the invention is to provide an improved flexure support for a photographic mask theta plate in an optical projection printing unit.